Main.elm

module Main exposing (..)

import Form exposing (..)
import Form.Input as Input
import Form.Validate exposing (..)
import Html exposing (..)


type Color
    = Red
    | Green
    | Blue


colors : List Color
colors =
    [ Red
    , Green
    , Blue
    ]


type alias Output =
    List Color


type alias Model =
    { outputForm : OutputForm }


type MyError
    = InvalidColor


type alias OutputForm =
    Form MyError Output


checkboxList : List ( String, value ) -> Validation e (List value)
checkboxList items =
    let
        validateItem ( key, value ) =
            field key
                (bool
                    |> andThen
                        (\checked ->
                            if checked then
                                succeed (Just value)
                            else
                                succeed Nothing
                        )
                )
    in
        sequence (List.map validateItem items)
            |> Form.Validate.map (List.filterMap identity)


validate : Validation e Output
validate =
    let
        colorsOptions =
            List.map (\c -> ( toString c, c )) colors
    in
        field "colors" (checkboxList colorsOptions)


sequence : List (Validation e a) -> Validation e (List a)
sequence validations =
    List.foldr (Form.Validate.map2 (::)) (Form.Validate.succeed []) validations


update : Form.Msg -> Model -> Model
update msg model =
    let
        _ =
            Debug.log "form msg" msg
    in
        { model | outputForm = Form.update msg model.outputForm }


initialModel : Model
initialModel =
    { outputForm = Form.initial [] validate }


view : Model -> Html Form.Msg
view { outputForm } =
    div
        []
        [ Input.dumpErrors outputForm
        , pre [] [ text (toString (Form.getOutput outputForm)) ]
        , div []
            (colors
                |> List.map
                    (\color ->
                        label
                            []
                            [ Input.checkboxInput (Form.getFieldAsBool ("colors." ++ toString color) outputForm) []
                            , text (toString color)
                            ]
                    )
            )
        ]


main : Program Never Model Form.Msg
main =
    beginnerProgram
        { model = initialModel
        , update = update
        , view = view
        }